This sounds like the famous Black Queen Murder Mystery in Lancashire, 1990, in which our Hero, Raymondo, was asked by the local plod to use his incredible brain to work out the clues left on a piece of paper in a cell by a murder suspect in order to locate where the body had been buried. I`m not sure how much help he was, although it seems the police were pleased with his efforts. Scarily, there was talk at the time of Raymondo`s efforts being turned into a filmscript ( who would have played him, I wonder...?) but thankfully nothing came of it.